System for earth penetration in deep water at atmospheric pressure

ABSTRACT

The system enables underwater mining or other earth penetration to be conducted at atmospheric pressure in deep water through a hollow cylindrical entry column formed of concentric, radially spaced, cylindrical tubes extending from above water into the bottom and containing in the spaces therebetween water columns of progressively decreasing depth toward the center for offsetting the static pressure of the surrounding water. Constructible in situ, the column serves as a monopod adapted to support above water a platform on which any suitable structure can be mounted. The column is stabilized against dynamic lateral forces by jets, anchors or other counteracting devices and is removable for salvage or reuse elsewhere on completion of a particular operation.

United States Patent Peter 1 1 Aug. 20, 1974 [54] SYSTEM FOR EARTH PENETRATION lN 3,552,129 1/1971 Hooper 61/34 DEEP WATER AT ATMOSPHERIC 3,553,968 1/1971 Armistcad 6l/46.5

PRESSURE Primary Examiner lacob Shapiro Attorney, Agent, or FirmWilmer Mechlin [57] ABSTRACT The system enables underwater mining or other earth penetration to be conducted at atmospheric pressure in deep water through a hollow cylindrical entry column formed of concentric, radially spaced, cylindrical tubes extending from above water into the bottom and containing in the spaces therebetween water columns of progressively decreasing depth toward the center for offsetting the static pressure of the surrounding water. Constructible in situ, the column serves as a monopod adapted to support above water a platform on which any suitable structure can be mounted. The column is stabilized against dynamic lateral forces by jets, anchors or other counteracting devices and is removable for salvage or reuse elsewhere on completion of a particular operation.

9 Claims, 3 Drawing Figures iaaomsa PATENTEB M820 1914 FIG. 1

FIG. 2

FIG. 3

Inventor; Philip W. Peter his AHorney SYSTEM FOR EARTH PENETRATION IN DEEP WATER AT ATMOSPHERIC PRESSURE This application is a continuation of my copending application Ser. No. 19,012, filed Mar. 12, 1970 and now abandoned.

BACKGROUND OF THE INVENTION Although fixed drilling platforms used in shoal waters ordinarily are supported on one or more piles or columns sunk into the bottom, Elliott, US. Pat. No. 3,165,898 proposes as a support a column having a downwardly opening frusto-conical base adapted to rest on the bottom and having a multiplicity of watertight compartments, by alternate flooding and emptying of which the base can either be ballasted to the bottom or floated from placeto place. With the broad base providing lateral stability and suitably reinforced against static forces, Elliott also proposes the use of its open bottom in the manner of a diving bell for direct access to the bottom of a body of water.

As opposed to the alternatives available for shoal water use, drilling in deep water in ocean, sea and lake beds, in exploring for oil and minerals, heretofore has been conducted from ships or other floating platforms, but, because of the enormous hydrostatic bottom pressures, the earths riches under deep water have scarcely been touched. I

To cope with the hostile environment, it heretofore has been proposed to recover mineral and other riches in deepwater beds by sinking onto the bottom decompression chambers, pressurized entry bulbs or other structures capable of withstanding the enormous, hydrostatic pressures and serving the structures by units of the cable-diving-bell type. While possibly suitable for exploration, these proposals, at least for mining, are not suited for the high production rates required for economical operation. It is with the provision for bottom penetration in deep water in an environment suitable for the application of operating procedures practiced in land-based operations that the present invention is concerned.

SUMMARY OF THE INVENTION The primary object ofthe present invention is to provide an improved system for deepwater earth penetration whereby an area of the bottom is made containable in and accessible and open to atmospheric pressure through a hollow entry column without requiring the column to have sufficient wall strength to withstand the hydrostatic pressure of the surrounding water.

Another object of the invention is to provide a deepwater earth penetration system having a plural-walled hollow entry column wherein the bottom area presented for working at atmospheric pressure is contained within the entry column and the walls are radially spaced, concentric cylindrical tubes extending from above water into the bottom and containing therebetween water columns of progressively decreasing depth toward the center, whereby the static pressure to which each tube is subjected is reduced to the difference between the pressures on its opposite sides.

An additional object of the invention is to provide a system for deepwater earth penetration at atmospheric pressure through a hollow entry column which not only uses columns of water separated by thin-walled cylindrieal tubes of progressively decreasing depth toward the center for reducing the static pressure of the surrounding water, but also provides by the entry column a stable support for mounting above water any structure suitable for the particular operation.

A further object of the invention is to provide a system for deepwater earth penetration at atmospheric pressure having a hollow entry column extending from above water into the bottom, which is adapted to withstand any dynamic, as well as static forces to which it may be subjected in service.

Other objects and features of the invention will appear hereinafter in detailed description, be particularly pointed out in the appended claims and be illustrated in the accompanying drawings, in which:

FIGURE DESCRIPTION FIG. 1 is a somewhat schematic side elevational view of a structure constructed in accordance with a preferred embodiment of the deepwater atmosphericpressure earth penetration system of the present invention, with portions broken away and shown in section to more clearly illustrate certain of the details of construction;

FIG. 2 is a horizontal sectional view taken 2-2 of FIG. 1, and

FIG. 3 is a horizontal sectional view taken along lines 3--3 of FIG. 1.

DETAILED DESCRIPTION Referring now to the details in the drawings in which like reference characters designate like parts, the improved system of the present invention for penetrating the earth at atmospheric pressure under deep water assumes the previous location in a deepwater bed, by underwater exploration or exploratory drilling from a ship or other floating platform, of a deposit of the earths riches of sufficient size to justify commercial exploitation and permits the deposit to be recovered economically in a contained environment similar to that of a land-based operation. Not only does the improved system enable deposits of oil or gas or a fluidizable solid to be drilled for and extracted in an environment protected from outside forces, from either the bottom or a stationary above-water platform, and permit well head equipment to be installed and serviced on the bottom, but it is especially adapted for mining from the bottom deposits of minerals or other solids required to be hoisted rather than pumped to the surface.

The improved system is intended to provide a fixed structure affording access at atmospheric pressure from the surface to the bottom during working of a particular deposit. In use the structure therefore will be subjected to two types of forces, one, static forces increasing toward the bottom from the hydrostatic pres sure of the surrounding water, and the other, dynamic lateral forces concentrated near the surface of the water from the action of wind, wave or current on surfaces exposed thereto.

lnstallable in deep water over the previously located deposit of resources, a structure constructed in accordance with the improved system is comprised of a hollow cylindrical entry column 1, which in operative position extends vertically from above water into the earth or bed 2 below the bottom or floor 3 of the particular body of water. The entry column I is constructed or formed of a plurality of concentric radially spaced cylindrical tubes 4, preferably uniform and coextensive in along lines height or length with the column and containing therebetween water columns of progressively decreasing height or depth toward the center of the column.

In spacing its tubes 4 by water columns 5 of progressively decreasing height or head toward the center, the entry column 1 makes use of the principle, applied to masonry dams, in bays between piers or buttresses thereof, in Church, Pat. No. 788,885 and Hennebique, Pat. No. 821,037, of offsetting the hydrostatic pressure of a water column on one side of a wall by that of a lower water column on its opposite side so as to reduce the resultant hydrostatic pressure on the wall at any level within the vertical limits of the lower water column to that produced by the difference in the heads of the two columns. As the hydrostatic pressure exerted by the water column is dependent upon its head and independent of its lateral dimensions and at any level is uniform in all directions, the water columns 5 between the tubes 4 would progressively decrease the hydrostatic pressure of the surrounding water on the column 1 even though the lateral spacing between adjoining tubes 4 were as little as a fraction of an inch.

Depending only on the number of its spaced tubes 4, the entry column 1, by utilizing the above principle, can step down the hydrostatic pressure of surrounding water of any depth to any desired extent. Thus, on an ocean bottom a mile deep at which level the hydrostatic pressure of the surrounding water will be 2366.7 lbs/sq. in., the entry column 1 can have its hollow interior 6 at atmospheric pressure, which at that level will be a mere l7.85 lb./sq. in. and the maximum effective hydrostatic pressure on each tube will be only that resulting from the difference in the heads of the water columns on its opposite sides. By suiting the number of the tubes to the depth of the water over the deposit of mineral or other resources to be worked and controlling the heights of the water columns between the tubes so that each is subjected to substantially the same effective static pressure, each of the tubes, since cylindrical and having a correspondingly high section modulus and, for a given thickness, maximum resistance to bending under the imposed hydrostatic forces, can be and preferably is thin-walled for minimizing weight and cost.

The individual tubes 4 conveniently may be formed by welding or otherwise bonding together appropriately curved thin sheets of metal or other material suitable for affording in the completed tubes the strength and corrosion-resistance required for the particular installation. When the tubes 4 are assembled into the entry column 1, each tube is connected to adjoining or confronting tubes for maintaining the spacing therebetween, preferably by longitudinally spaced sets of radially extending, circumferentially spaced struts, crossbraces, or spacers 7. To the extent practical, the tubes may be fabricated and the entry column assembled on shore and towed as a whole or in sections to the site of the deposit. However, while some prefabrication of components, such as bending of the sheets, can be performed ashore, the ultimate size of the entry column usually will require it to be constructed at the site on a ship or other floating platform and there be lowered or sunk progressively or in increments into the water as construction proceeds.

On continued construction, the entry column 1 will reach and penetrate of its own weight into the bottom, with the weight concentrated on the ends of the tubes at its otherwise open lower end 8. When that penetration stops, the construction of the entry column usually will be continued until its overall height or length will provide both the desired final above water height and the additional below water depth required to compensate for any further penetration of the bottom by the tubes, either estimated or, if available, indicated by previous tests to be possible by imposing vertical loading on the column.

The entry column 1 extends at this stage below the bottom 3 of the body of water at its lower end 8 and above the surface 9 of that body at its upper end 10 and, with the tubes 4 extending its full length and connected by the struts 7, has a very high section modulus, andpossesses great strength and resistance to both compressive and bending forces. It, thus, is well adapted to serve as a giant monopod presenting at its upper end 10 an above-water base for supporting a platform 1]. In turn, any desired structure 12 can be mounted or erected on the platform, including a building, such as illustrated, of sufficient size to contain administration and living quarters and a mill or other processing plant of a self-contained operation.

When constructed, the platform 11 and any structure 12 thereon, will add to the weight of the entry column 1 and correspondingly increase the vertical force urging the lower end 8 of the column into the bottom 3 and the underlying bed 2. If further settlement is anticipated, final settlement, to the point at which the earths density refuses penetration by force, should be accomplished at this time to ensure vertical stability when the column is in use. This is readily accomplishable by adding water loading to the upper end 10 of the column. Prior to this time. no water loading has been available, since, with both ends then open, water is free to enter the open lower end or bottom 8 of the entry column during sinking and, when the entry column reaches the water bottom or floor 3, its cylindrical interior 6 and the annular spaces 13 between the tubes 4 are simply filled to the level of the water surface 9. For the entry column to perform as intended, it therefore is necessary to pump out the water in the interior 6 and pump down the water in each of the annular spaces 13 to the level at which each water column 5 will have the proper head for the contemplated progressive decrease toward the center of the hydrostatic pressure of the water surrounding the column. The desired added water loading for final settlement is most conveniently accomplishable during such pumping by directing part of the water into temporary or permanent tanks 14 on the platform 11 and diverting the balance from the column into the surrounding water.

Once the water has been pumped out of the entry column 1, any muck at the bottom of the interior 6 also will be pumped out until solid ground is reached and, if needed, the latter can be sealed against seepage, as by pressure grouting 15 applied by deephole drilling. At this juncture, the entry column 1 will be vertically stable, and its interior 6, protected from the hydrostatic pressure of the surrounding water at all levels by the combined bending resistance of the tubes 4 and the progressively reduced heads of the water columns 5 therebetween, will form a cylindrical central access tube, opening, or bore, open to atmosphere at the top and at atmospheric pressure from top to bottom, with only a nominal difference between the interior pressures at top and bottom. With the static forces of the surrounding water offset, the entry column 1 will still be exposed at the bottom to the tendency of the surrounding water under the imposed hydrostatic pressure to move laterally toward the columns hollow interior or central bore 6 through the underlying mud. However, such lateral movement of water will be hampered by the density of the mud, as well as by the progressive decrease in the driving force as the water moves toward the center under water columns of progressively decreasing depth. Thus, with the very considerable radius that the entry column must have, there is little likeli hood of excessive intake in the bottom of the interior or access tube 6 and, should this occur, it can readily be stopped by suitable sealing means, such as the indicated pressure grouting 15. The earth contained within the bottom of the access tube 6 thereafter can be penetrated under atmospheric conditions in any manner suitable for the deposit to be worked.

As indicated earlier, the entry column 1, in place, will be subjected not only to static forces from the surrounding water but also to dynamic forces from wind, wave or current. Except in the unlikely event that the entry column is located in the path of a strong deep current, such as the Gulf Stream, the dynamic forces will be concentrated adjacent the water surface 9. In any case, with its large radius and lower end sunk into the bottom, the column itself will have great lateral stability. If additional lateral stabilizing is found necessary in a particular location, it readily can be provided either constantly, by exterior anchor lines connected to the entry column or, as needed, by means mounted in the column and adapted to counter any continuous or sporadic external dynamic forces. Among countermeans suitable for the problem are motor-driven propellers or the illustrated pump-powered, jet-emitting, directional nozzles 16, any desired number either of which is conveniently mountable in circumferentially spaced relation in the outermost of the annular spaces 13 above the head of the water column 5 therein.

The height of the entry column 1 will of course be governed by the depth of the water in the particular location and that factor and the structure it is to mount will be the main determinants'of its diameter. Another factor affecting the diameter will be the radial spacing of the tubes 4. As pointed out earlier, this spacing can be minimal without detriment to the combined ability of the tubes of the entry column and the contained water columns 5 to achieve atmospheric pressure in the open central access tube 6. However, as a structure or installation constructed in accordance with the improved system must be of fairly long duration to justify its expense and inspection of the tubes 4 may be necessary, the preferred radial spacing of the tubes will be on the order of from 5 to feet for ready access therebetween, in which case the entry column can easily be several hundred feet in diameter. It also is desirable that the installation include instrumentation and pumps (not shown) for automatically regulating or controlling the heads of the several water columns 5.

The internal structure installed in the atmospheric pressure access tube 6 will depend on the nature of the deposit to be extracted, but, for transport of personnel, equipment and materials between top and bottom, can be expected to include at least one and preferably the illustrated counterbalanced pair of high-speed hoists 17. If, as in the structure of the illustrated embodiment, the deposit is of minerals or other solids requiring mining, the hoist shaft 18 will be continued downwardly below bottom level by a shaft 19 to the level of the deposit and connected thereto by suitable tunneling 20. In the illustrated self-contained structure, the solids removed from the deposit will'be hoisted to the top for processing in a plant in the building 12 and the gangue or other waste either dumped overboard or pumped back to fill mined-out stopes. Since conducted under comparable atmospheric conditions within the access tube 6, the mine or other penetration through the earth contained in the bottom of the tube can include the safety features usual in like onshore installations.

When the deposit has been worked to the extent practical, the size of the entry column 1 ordinarily will prevent it or the structure as a whole from being towed to another location, even though, by sealing the column at top and bottom and pumping down the contained water, the column can be given sufficient buoyance to lift it from the bottom. Consequently, instead of being towed, the structure usually will be salvaged by being dismantled by a salvage ship and moved in parts to another location. In such case, the column either can be rendered buoyant for lifting it from the bottom or, by installing a cutting explosive charge at bottom level during the initial installation, can have the tubes sev ered at that level, and allow the freed portion there-- above to be hoisted for salvage.

From the above detailed description, it will be apparent that there has been provided an improved system for penetrating the earth under deep water which permits bottom operations to be conducted under atmospheric conditions regardless of the external static and dynamic forces to which the structure of the system is subjected. It should be understood that the described and disclosed embodiment is merely exemplary of the invention and that all modifications are intended to be included that do not depart from the spirit of the invention and the scope of the appended claims.

Having now described my invention, 1 claim:

1. A system for deepwater earth penetration at atmospheric pressure, comprising constructing of a plurality of axially coextensive radially spaced concentric cylindrical thinwalled tubes an open-ended cylindrical entry column having a hollow interior and a length to extend from above the surface into the bottom of a body of water at a location to be penetrated, sinking said column vertically into said water body with said tubes open at both ends for enabling said tubes during lowering to be continuously filled with water from below to the level of said surface and lower ends of said tubes on reaching the bottom of said body to penetrate thereinto under the weight of said column and thereby close said lower ends, and thereafter partly pumping out said column to empty said interior thereof and pumping down the water between said tubes to form water columns of progressively decreasing height toward the center thereof for correspondingly reducing toward said center the hydrostatic pressure exerted on the exterior of said entry column by the surrounding water.

2. A system according to claim 1, including connecting adjoining tubes by cross-brace means for radially spacing the tubes, selecting each tube to have a bending resistance sufficient to withstand the hydrostatic pressure exerted thereon by the difference in the heights of the water columns on opposite sides thereof, and by combining the bending resistance of the tubes and progressive decrease in the heads of the water columns therebetween reducing the static pressure on the exterior of the entry column substantially to atmospheric pressure over the length of the hollow interior between the surface and bottom of the water body.

3. A system according to claim 2, wherein the entry column is constructed on the surface of and sunk progressively into the body of water.

4. A system according to claim 3, including constructing a platform above water on the upper end of the entry column, and installing tank means on said platform for adding water loading to the downward force urging the lower end of the column into the earth underlying the bottom of the body of water.

5. A system according to claim 4, including filling said tank means with water from said entry column during said pumping out thereof.

6. A system according to claim 3, including connecting counteracting means to the entry column for counterbalancing external dynamic forces thereon.

7. A system according to claim 6, wherein the counteracting means are directional means mounted in and spaced circumferentially about the entry column.

8. A system according to claim 6, including constructing a platform on the upper end of the entry colneath the entry column.

v j? .-UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 33330 0 Dated Aug. 20 1974 Invent (s) I Philip W1 Peter It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Inventor's'street address is 128 San Diego Signed and sealed this 31st day of December 1974.

(SEAL) Attest:

McCOY M. GIBSON" JR. 0. MARSHALL DANN Attesting Officer Commissioner of Patents FORM PO-10 0 I USCOMM-DC 60376-P69 u.s.covs'nnMEN1 PRINTING orncz: 93 o 

1. A system for deepwater earth penetration at atmospheric pressure, comprising constructing of a plurality of axially coextensive radially spaced concentric cylindrical thin-walled tubes an open-ended cylindrical entry column having a hollow interior and a length to extend from above the surface into the bottom of a body of water at a location to be penetrated, sinking said column vertically into said water body with said tubes open at both ends for enabling said tubes during lowering to be continuously filled with water from below to the level of said surface and lower ends of said tubes on reaching the bottom of said body to penetrate thereinto under the weight of said column and thereby close said lower ends, and thereafter partly pumping out said column to empty said interior thereof and pumping down the water between said tubes to form water columns of progressively decreasing height toward the center thereof for correspondingly reducing toward said center the hydrostatic pressure exerted on the exterior of said entry column by the surrounding water.
 2. A system according to claim 1, including connecting adjoining tubes by cross-brace means for radially spacing the tubes, selecting each tube to have a bending resistance sufficient to withstand the hydrostatic pressure exerted thereon by the difference in the heights of the water columns on opposite sides thereof, and by combining the bending resistance of the tubes and progressive decrease in the heads of the water columns therebetween reducing the static pressure on the exterior of the entry column substantially to atmospheric pressure over the length of the hollow interior between the surface and bottom of the water body.
 3. A system according to claim 2, wherein the entry column is constructed on the surface of and sunk progressively into the body of water.
 4. A system according to claim 3, including constructing a platform above water on the upper end of the entry column, and installing tank means on said platform for adding water loading to the downward force urging the lower end of the column into the earth underlying the bottom of the body of water.
 5. A system according to claim 4, including filling said tank means with water from said entry column during said pumping out thereof.
 6. A system according to claim 3, including connecting counteracting means to the entry column for counterbalancing external dynamic forces thereon.
 7. A system according to claim 6, wherein the counteracting means are directional means mounted in and spaced circumferentially about the entry column.
 8. A system according to claim 6, including constructing a platform on the upper end of the entry column, and mounting a structure suitable for a particular operation on said platform.
 9. A system according to claim 8, wherein the hollow interior of the entry column forms a cylindrical access tube extending from the surface to the bottom of the body of water and at atmospheric pressure over the length thereof, and including injecting sealing means in the bottom of said access tube for resisting seepage thereinto of water moving laterally theretoward beneath the entry column. 